Follow the instructions on the box for defrosting the phyllo. Preheat oven to 400F.

Combine defrosted spinach (I heated it in the bowl I used to combine everything in the microwave for 4 minutes and it was plenty warm), feta, egg, onion, salt, and pepper in a bowl and set aside.

On a greased (I used olive oil) cookie sheet, fold one sheet of phyllo in half crosswise and lightly brush with butter. Repeat with 2 more pieces. Scoop about 1/4 cup (or use your discretion, just beware of over-filling) of spinach mixture onto one end of the phyllo, leaving about a 1-2 inch border. Fold the other end of the phyllo sheets over the top and fold edges under. Repeat until filling is used up (I got 7 pockets out of it). Brush tops of pockets lightly with more butter.

Bake for about 30 minutes, or until golden-tan and crispy. Watch out! These suckers are HOT when they come out, and it takes them a while to cool. Leave plenty of time before serving to kids, particularly. Cutting them in half helps.